This invention relates to an apparatus and process for packaging articles, particularly of the type which are adversely affected by oxygen, in substantially oxygen-free, gas containing flexible containers, and it more specifically relates to an apparatus and process for packaging fresh meat pieces, such as fresh red meat, in flexible containers wherein the meat may be held for extended periods of time without having the bacteria levels on or in the meat exceed acceptable limits and without having a significant adverse effect on the desired color of the fresh meat.
It is well known that there are a great number of materials that are adversely affected by the atmosphere, particularly humidity conditions and the oxygen therein. Such materials include metals, such as precious metals, which undesirably oxidize in air, and a great variety of food products, such as fresh fruits and vegetables, nuts, crackers, cured meats, fresh meats, including poultry, beef, pork, veal, and lamb, and like products.
In the case of food products, the oxygen and humidity conditions have undesired effects on the food. Particularly in the case of meat, the oxygen in the air supports the growth of bacteria on the surface of the meat, in particular, and the bacteria growth can increase to such a point that the meat becomes "spoiled" and/or the fat becomes rancid. There are many machines and processes known for packaging products, such as fresh and cured meats, in a wide variety of vacuumized, gas flushed, and/or sealed containers of various types. Canning, for example, is a well known technique for preserving food products. In order to preserve meat, various curing and preserving techniques have been used to preserve the meat over extended periods. Well known packaging techniques, primarily for consumer purchase include placing the products in flexible bags or containers. Also, vacuumizing the container to substantially eliminate bacteria growth supporting oxygen is well known. Gas flushing with preserving gases, as carbon dioxide, is also known. It is common to heat seal the thus vacuumized or gas flushed container containing sliced bacon, wieners, or the like. In essence, the preservation of foodstuffs, including fresh and cured meats, for extended periods of time is a well known and well developed art.
With particular emphasis on the preservation of fresh red meat, the storage problem has two stages. First, the meat must be properly preserved from the time the animal is processed and shipped from a packing plant to the ultimate user, such as a butcher shop or a restaurant. Although one preserving technique is to freeze the meat, probably most of the meat sold through butcher shops and consumed in restaurants is fresh meat, not previously frozen. Freezing is considered to have certain disadvantages in that the color and taste are often considered to be adversely affected by freezing. Additionally, freezing fresh meat is generally considered to be an expensive operation, requiring expensive freezing and storage equipment and also requiring considerable use of energy during freezing and during storage. Thus, meat which is shipped from a packing plant is more conventionally preserved, by refrigeration, at above freezing temperatures, as about 35.degree.-50.degree. F., until the food is prepared for serving, as in a restaurant, or until the meat is prepared for consumer purchase, as in a butcher shop.
Most of the meat shipped in bulk from a packing plant is preserved by refrigerating temperatures and not by absence of oxygen. The meat is preserved in this way so the bacteria level on or in the meat or poultry does not exceed levels which would be injurious to human health. Some of the injurious bacteria are aerobic, that is, air or oxygen is required for growth. The absence of oxygen, however, is generally considered to actually cause discoloration of fresh red meat product and this also is an undesirable result. Some reseachers have also considered that excessive concentrations of carbon dioxide cause greying or darkening of the meat, even after relatively short periods of time. Thus, fresh red meat presents two particularly difficult problems for packaging thereof, that is, excessive bacteria growth and meat discoloration.
The bacteria growth and discoloration problems are even more pronounced when retail butcher shops and restaurants "age" their meat for a sufficient period of time to permit the natural enzymes of beef to break down the cells or connective tissue until the beef is particularly tender and palatable. It is generally considered that such natural aging of beef for extended periods of time is highly preferable over artificial tenderization procedures, such as injection with various proteolytic enzymes. One significant problem with natural aging of beef is that the meat ordinarily, even under refrigeration, has considerable discoloration and bacteria or mold growth on the exposed surfaces of the meat. This is because the "aging" normally takes place in a refrigerated, oxygen-containing room or cooler, resulting in bacteria growth. Before the meat can be consumed, the butcher trims off not only the mold, but also a considerable portion of the meat adjacent the mold growth. As a result, there is a considerable loss in the amount of meat which can be consumed, as compared to the original cut. This leads to excessive prices for such meat for the consumer.
Although various techniques, including vacuum packaging, have been used at the retail level for preserving smaller amounts of meat, as for consumer packages of meat, bulk shipments of fresh poultry and meat have generally not involved vacuum packaging of the product. Generally, large bulk shipments of beef or pork have been in refrigerated vehicles. Some prior art has also suggested the inclusion of an atmosphere of gases, such as carbon dioxide, nitrogen, or the like. A significant disadvantage of maintaining a controlled gaseous atmosphere in a storage compartment, as in a butcher's cooler or in a vehicle, is that the controls for maintaining the compartment at the desired conditions of gas level, temperature, and humidity, for example, can be quite expensive and complex. Large pieces of fresh meat have also been packaged in vacuumized packages. For example, beef rib sections have been packaged in such a way. One quite well known system includes placing individual meat pieces into a flexible plastic bag, the bag is vacuumized and then a wire clip is placed around the gathered end of the bag. One of the disadvantages of this system is that, with the clipping arrangement, it is difficult to maintain a vacuum because the bag is only gathered and the vacuum is lost therethrough. Additionally, the system is principally adapted for packaging individual meat pieces and does not adapt to packaging of larger meat pieces or to bulk packaging a plurality of relatively large pieces of meat. In the case of vacuumized bags, the bag is generally taut and subject to splitting or breakage, thereby losing the vacuum and making the meat therein susceptible to undue bacteria growth.
The known equipment often requires some skill in operation. Such equipment also requires considerable floor space and usually requires a heated tunnel for shrinking the bag around the packaged product. Such heat tunnels are generally placed in a refrigerated room, causing additional undesirable expenses for maintaining the refrigerated room at the desired temperature, to offset heat from the heat tunnel, and at the same time, expenses are required for heating the heat tunnel to the desired level to offset the temperature of the refrigerated room. Also, in the separate packaging of individual meat pieces, there is a significant disadvantage in that labor expenses are high because each single piece requires a separate vacuumizing and sealing operation. Individual handling of each meat piece during packaging is clearly time and labor consuming and therefore undesirable.